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Old 02-20-2001, 10:44 PM   #14
XT6Wagon
Scooby Specialist
 
Member#: 524
Join Date: Nov 1999
Location: WA
Vehicle:
04 STi
White

Post

Ok, what volume of air do you think you are pressureising?? The volume of the combustion chamber is the SMALLEST portion of the whole thing. The Intercooler, piping, intake manifold all are larger than the 1/4 of the displacement. Note that since the motor is a batch mode, only one cylinder is gettign air at one time.

Lets see:

8' of 2" pipe is 678.58 cubic inches
(might be closer than the pulled out of my ... er... hat figure of 10ft)

A 12"X24"X3" Intercooler with say an void raio (space inside the "box") of 40% would have a volume of
345.6 cubic inches

No idea what the intake manifold holds, but the plenium itself will be larger than 1/4 the displacement.

So you see all that pipeing has a HUGE affect on the volume pressurised.

Next up you are forgetting that one 90 degree elbow is more of a flow restriction than several ft of 2" pipe. I estimate it would take 7!! 90 degree bends to make a FMIC work. (normal intake manifold layout)

I will now talk about your idea that a bit of pressure loss does not matter. If you are amkign 20 psi in the intake manifold (correct place to measure boost), the turbo will have to put out 23 or so with a decent IC, and minimal piping. If you add several feet of pipe, several bends, and a much larger IC you will likely need over 25 psi at the turbo.
The TEMPATURE of the air coming out of the turbo is a product of pre-compression temp, pressure ratio of the compressior, and the efficency of the compressor. So the extra pressure loss hits you two ways. The extra boost will lower the efficency of the compressor as it will be farther away from the peak efficency island, and the pressure ratio is higher.

Next up to bat is the flipping the intake manifold. I think this is a REQUIRED operation to make a FMIC worth more than takign a leak on an angry pitbull. However I have heard that the A/C must be removed, and the alternator and PS pump must be mounted different. This seems like a non-possiblity for most people with a street car.

I will end with a bit of REAL WORLD evidence of the effectiveness of the TMIC. Look at the two SCC Impreza'a. The 99 was making abotu the same power (peak), with far less lag, a healthier mid range, and less problems with a small top mount, in comparision to the 98 with the FMIC. I hope Shiv can slap a better rendition of the two cars here.

Oh and I don't CARE what the people in austrailia do, after all people here are stupid enough to use chips in a VW 1.8T that make the turbo glow for over 2min after a high boost run. Just because its popular or believed does not make it true.
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